Asymmetric catalysis heterogeneous

The coordination of ligands at the surface of metal nanoparticles has to influence the reactivity of these particles. However, only a few examples of asymmetric heterogeneous catalysis have been reported, the most popular ones using a platinum cinchonidine system [65,66]. In order to demonstrate the directing effect of asymmetric ligands, we have studied their coordination on ruthenium, palladium, and platinum nanoparticles and the influence of their presence on selected catalytic transformations. 

Asymmetric Heterogeneous Catalysis Using Supported Metal Complexes... 

The transformations that use asymmetric heterogeneous catalysis will be highlighted P-keto esters and diketone reductions by Raney nickel catalyst modified with R,R-tartaric acid and NaBr. a-Keto acid reductions with cinchona modified Pt catalysts are discussed in Chapter 18. 

Heitbaum M, Glorius E, Escher I. Asymmetric heterogeneous catalysis. Angew. Chem., Int. Ed. 2006 45 4732-4762. 

M. Nielsen, A. H. Thomsen, T. R. Jensen, H. J. Jakobsen, J. Skibsted, K. V. Gothelf, Pormation and structure of conjugated salen-cross-linked polymers and their application in asymmetric heterogeneous catalysis, Eur. ]. Org. Ghem. (2005) 342. 

Handbook of Asymmetric Heterogeneous Catalysis. Edited by K. Ding and Y. Uozumi Copyright 2008 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31913-8... 

It is the goal of this chapter to present an overview of asymmetric heterogeneous catalysis using inorganic supports, thereby portraying the state of the art and discussing its potential and limitations. 

If an asymmetric catalyst acts perfectly well from the point of view of enanti-oselectivity and activity, there remains one difficulty to overcome, namely the recovery and the reuse of the catalyst. This can be achieved by asymmetric heterogeneous catalysis. This old approach, where a metal was modified by a chiral additive [12,14], has been reappraised recently, giving interesting results, but the scope of the reaction remains very narrow (see the review in Ref. [ 122]). 

A Baiker. Progress in asymmetric heterogeneous catalysis Design of novel chirally modified platinum metal catalysts. J Mol Catal A Chem 115 473-493,1997. 

The synthetic method described above is very simple and can be in principle transposed to any metal/ligand combination. One of the most challenging problems regarding the use of nanoparticles in catalysis concerns asymmetric catalysis. Only a few examples of asymmetric heterogeneous catalysis have been reported, the most popular ones based on a platinum cinchonidine system. Using the chiral xylofuranoside diphosphite ligand, Pd nanoparticles with a... 

Asymmetric heterogeneous catalysis has been demonstrated by the enantioselec-tive and racemic hydrogenation of ethyl pyruvate over Pt-Al203 catalyst. Higher reaction rate and enantioselectivity (75%) were observed in nonpolar solvent (toluene) whereas in a polar solvent (ethanol) they decreased substantially (Scheme 13.5) [58]. 

Herault,D., Saluzzo,C., Duval,R., Lamaire,M. (2002) Enantiopine beds a tool for asymmetric heterogeneous catalysis, J. Mol. Catal. A. Chem. 182-183, 249-256. 

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